#include "./md5.h"
#include <string.h>

namespace utils::md5 {

#define F(x, y, z) ((x & y) | (~x & z))
#define G(x, y, z) ((x & z) | (y & ~z))
#define H(x, y, z) (x^y^z)
#define I(x, y, z) (y ^ (x | ~z))
#define ROTATE_LEFT(x, n) ((x << n) | (x >> (32-n)))
#define FF(a, b, c, d, x, s, ac) \
    { \
        a += F(b,c,d) + x + ac; \
        a = ROTATE_LEFT(a,s); \
        a += b; \
    }
#define GG(a, b, c, d, x, s, ac) \
    { \
        a += G(b,c,d) + x + ac; \
        a = ROTATE_LEFT(a,s); \
        a += b; \
    }
#define HH(a, b, c, d, x, s, ac) \
    { \
        a += H(b,c,d) + x + ac; \
        a = ROTATE_LEFT(a,s); \
        a += b; \
    }
#define II(a, b, c, d, x, s, ac) \
    { \
        a += I(b,c,d) + x + ac; \
        a = ROTATE_LEFT(a,s); \
        a += b; \
    }

using namespace std;

static const uint8_t PADDING[] = {0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

static uint32_t count[2];
static uint32_t state[4];
static uint8_t buffer[64];
static uint32_t x[64];
static uint8_t bits[8];				

static void md5_transform(uint32_t state[4], const uint8_t block[64], uint32_t *x);		
static void md5_decode(uint32_t *output, const uint8_t *input, uint32_t len);
static void md5_encode(uint8_t *output, const uint32_t *input, uint32_t len);

void md5_init();								  
void md5_final(uint8_t digest[16]);
void md5_update(const void *input, uint32_t size);
								  
void sum(const void *data, uint32_t size, uint8_t digest[16]) {
	md5_init();
	md5_update(data, size);
	md5_final(digest);
}
								  
void md5_init() {
	count[0] = 0;
	count[1] = 0;
	state[0] = 0x67452301;
	state[1] = 0xEFCDAB89;
	state[2] = 0x98BADCFE;
	state[3] = 0x10325476;
}								  
								  
void md5_final(uint8_t digest[16]) {
	uint32_t index = 0, padlen = 0;
	index = (count[0] >> 3) & 0x3F;
	padlen = (index < 56) ? (56 - index) : (120 - index);
	md5_encode(bits, count, 8);
	md5_update(PADDING, padlen);
	md5_update(bits, 8);
	md5_encode(digest, state, 16);
}								  
								  
void md5_update(const void *input, uint32_t size) {
	uint32_t i = 0, index = 0, partlen = 0;
    auto in = static_cast<const uint8_t *>(input);
    index = (count[0] >> 3) & 0x3F;
    partlen = 64 - index;
    count[0] += size << 3;
    if (count[0] < (size << 3)) {
        count[1]++;
	}
    count[1] += size >> 29;

    if (size >= partlen) {
		memcpy(&buffer[index], input, partlen);
		md5_transform(state, buffer, x);
		for (i = partlen; i + 64 <= size; i += 64) {
			md5_transform(state, in + i, x);
		}
		index = 0;
    } else {
		i = 0;
	}
	memcpy(&buffer[index], &in[i], size - i);
}								  
								  
static void md5_encode(uint8_t *output, const uint32_t *input, uint32_t len) {
	uint32_t i = 0, j = 0;
	while (j < len) {
		output[j] = input[i] & 0xFF;
		output[j + 1] = (input[i] >> 8) & 0xFF;
		output[j + 2] = (input[i] >> 16) & 0xFF;
		output[j + 3] = (input[i] >> 24) & 0xFF;
		i++;
		j += 4;
	}
}
								  
static void md5_decode(uint32_t *output, const uint8_t *input, uint32_t len) {
    uint32_t i = 0, j = 0;
    while (j < len) {
        output[i] = (input[j]) |
           (input[j + 1] << 8) |
           (input[j + 2] << 16) |
           (input[j + 3] << 24);
		i++;
		j += 4;
	}
}

static void md5_transform(uint32_t state[4], const uint8_t block[64], uint32_t *x) {
    uint32_t a = state[0];
    uint32_t b = state[1];
    uint32_t c = state[2];
    uint32_t d = state[3];
	
    md5_decode(x, block, 64);
	
    FF(a, b, c, d, x[0], 7, 0xd76aa478); /* 1 */
    FF(d, a, b, c, x[1], 12, 0xe8c7b756); /* 2 */
    FF(c, d, a, b, x[2], 17, 0x242070db); /* 3 */
    FF(b, c, d, a, x[3], 22, 0xc1bdceee); /* 4 */
    FF(a, b, c, d, x[4], 7, 0xf57c0faf); /* 5 */
    FF(d, a, b, c, x[5], 12, 0x4787c62a); /* 6 */
    FF(c, d, a, b, x[6], 17, 0xa8304613); /* 7 */
    FF(b, c, d, a, x[7], 22, 0xfd469501); /* 8 */
    FF(a, b, c, d, x[8], 7, 0x698098d8); /* 9 */
    FF(d, a, b, c, x[9], 12, 0x8b44f7af); /* 10 */
    FF(c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
    FF(b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
    FF(a, b, c, d, x[12], 7, 0x6b901122); /* 13 */
    FF(d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
    FF(c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
    FF(b, c, d, a, x[15], 22, 0x49b40821); /* 16 */

    /* Round 2 */
    GG(a, b, c, d, x[1], 5, 0xf61e2562); /* 17 */
    GG(d, a, b, c, x[6], 9, 0xc040b340); /* 18 */
    GG(c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
    GG(b, c, d, a, x[0], 20, 0xe9b6c7aa); /* 20 */
    GG(a, b, c, d, x[5], 5, 0xd62f105d); /* 21 */
    GG(d, a, b, c, x[10], 9, 0x2441453); /* 22 */
    GG(c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
    GG(b, c, d, a, x[4], 20, 0xe7d3fbc8); /* 24 */
    GG(a, b, c, d, x[9], 5, 0x21e1cde6); /* 25 */
    GG(d, a, b, c, x[14], 9, 0xc33707d6); /* 26 */
    GG(c, d, a, b, x[3], 14, 0xf4d50d87); /* 27 */
    GG(b, c, d, a, x[8], 20, 0x455a14ed); /* 28 */
    GG(a, b, c, d, x[13], 5, 0xa9e3e905); /* 29 */
    GG(d, a, b, c, x[2], 9, 0xfcefa3f8); /* 30 */
    GG(c, d, a, b, x[7], 14, 0x676f02d9); /* 31 */
    GG(b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */

    /* Round 3 */
    HH(a, b, c, d, x[5], 4, 0xfffa3942); /* 33 */
    HH(d, a, b, c, x[8], 11, 0x8771f681); /* 34 */
    HH(c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
    HH(b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
    HH(a, b, c, d, x[1], 4, 0xa4beea44); /* 37 */
    HH(d, a, b, c, x[4], 11, 0x4bdecfa9); /* 38 */
    HH(c, d, a, b, x[7], 16, 0xf6bb4b60); /* 39 */
    HH(b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
    HH(a, b, c, d, x[13], 4, 0x289b7ec6); /* 41 */
    HH(d, a, b, c, x[0], 11, 0xeaa127fa); /* 42 */
    HH(c, d, a, b, x[3], 16, 0xd4ef3085); /* 43 */
    HH(b, c, d, a, x[6], 23, 0x4881d05); /* 44 */
    HH(a, b, c, d, x[9], 4, 0xd9d4d039); /* 45 */
    HH(d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
    HH(c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
    HH(b, c, d, a, x[2], 23, 0xc4ac5665); /* 48 */

    /* Round 4 */
    II(a, b, c, d, x[0], 6, 0xf4292244); /* 49 */
    II(d, a, b, c, x[7], 10, 0x432aff97); /* 50 */
    II(c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
    II(b, c, d, a, x[5], 21, 0xfc93a039); /* 52 */
    II(a, b, c, d, x[12], 6, 0x655b59c3); /* 53 */
    II(d, a, b, c, x[3], 10, 0x8f0ccc92); /* 54 */
    II(c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
    II(b, c, d, a, x[1], 21, 0x85845dd1); /* 56 */
    II(a, b, c, d, x[8], 6, 0x6fa87e4f); /* 57 */
    II(d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
    II(c, d, a, b, x[6], 15, 0xa3014314); /* 59 */
    II(b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
    II(a, b, c, d, x[4], 6, 0xf7537e82); /* 61 */
    II(d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
    II(c, d, a, b, x[2], 15, 0x2ad7d2bb); /* 63 */
    II(b, c, d, a, x[9], 21, 0xeb86d391); /* 64 */
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
}

}



